An Internet troll is either a person who sends messages on the Internet hoping to entice other users into angry or fruitless responses, or a message sent with such content. The term derives from the phrase "trolling for newbies" and ultimately from trolling for fish; it first appeared on Usenet. The term is frequently abused to slander opponents in heated debates and is frequently misapplied to those who are ignorant of etiquette.

Trolling is often described as an online version of the breaching experiment, where social boundaries and rules of etiquette are broken. Self-proclaimed trolls often style themselves as Devil's Advocates or gadflies or culture jammers, challenging the dominant discourse and assumptions of the forum they are trolling in an attempt to subvert and introduce different ways of thinking. Detractors who value etiquette claim that true Devil's Advocates generally identify themselves as such for the sake of etiquette, whereas trolls often consider etiquette to be something worth trolling in order to fight groupthink.

Trolls are sometimes caricatured as socially inept. This is often due to the fundamental attribution error, as it is impossible to know the real traits of an individual solely from their online discourse. Indeed, since intentional trolls are alleged to knowingly flout social boundaries, it is difficult to typecast them as socially inept since they have arguably proven adept at their goal.